In the case of hybrid vehicles, in particular in the case of electric vehicles, which are connected to domestically conventional sockets or the like (plug-in hybrid) for charging, charging is effected via external networks, for example the 220 V home network generally provided in the building. The batteries used in electric and also in hybrid vehicles are high-voltage batteries. Lithium ion cells, in particular, are currently used as high-voltage batteries.
Lithium ion battery cells may be damaged by excessively high charging currents. The battery cells may also be damaged by charging operations which last too long at excessively low temperatures. The damage occurring to the lithium ion battery cells may be such that an internal short circuit occurs in the battery cells. The internal short circuit may consequently result in a thermal chain reaction which is also referred to as “thermal runaway”. In the extreme case, the thermal chain reaction which has occurred may result in a fire in the battery cell and possibly adjacent cells, that is to say an entire battery module in a battery pack of a hybrid or electric vehicle. A battery management system is provided for operating battery cells and battery modules formed from the latter in electric vehicles and hybrid vehicles. The task of the battery management system is to monitor the individual battery cells in the individual battery modules in the battery pack and to prevent the danger, which was outlined above and constitutes an extreme case, by monitoring the safety-relevant parameters and reliably precluding charging or operation of the battery cells in the battery modules outside the predefined specifications. However, it is theoretically possible for a fire to nevertheless occur either as a result of an incorrect design or as a result of non-linear chemical effects, which can therefore be controlled only with difficulty, inside the individual battery cells or as a result of prior damage to the battery cell, as outlined above, for example as a result of a production fault. If electric vehicles or hybrid vehicles in the form of a “plug-in hybrid” are charged, for example, overnight in a building or in a parking space at a building or inside a garage of the building or else an underground car park, such a battery cell or battery module fire which occurs may result in a fire in the entire building, in which, in the extreme case, even people who are in the building by chance and are not warned in good time, for example at night, may be harmed.